Why is the Lucas test not recommended to differentiate higher alcohols?Doubts Regarding Ceric Ammonium Nitrate Test for AlcoholsWhy are tertiary alkyl halides obtained in higher yield than secondary or primary during free radical halogenation of alkanes?Identification of types of alcoholsLucas test for alcoholsWhy doesn't a halide anion react with primary or secondary alcohols using SN2?Nucleophilicity of alcoxy groupsUnknown alcohol sample. Chromic acid negative but iodoform positive?Is it correct to say that ethenol is an alcohol?Doubts Regarding Ceric Ammonium Nitrate Test for Alcohols
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Why is the Lucas test not recommended to differentiate higher alcohols?
Doubts Regarding Ceric Ammonium Nitrate Test for AlcoholsWhy are tertiary alkyl halides obtained in higher yield than secondary or primary during free radical halogenation of alkanes?Identification of types of alcoholsLucas test for alcoholsWhy doesn't a halide anion react with primary or secondary alcohols using SN2?Nucleophilicity of alcoxy groupsUnknown alcohol sample. Chromic acid negative but iodoform positive?Is it correct to say that ethenol is an alcohol?Doubts Regarding Ceric Ammonium Nitrate Test for Alcohols
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I read about the Lucas test for alcohols in which a cloudy precipitate is produced with a tertiary or secondary alcohol. However, on a side note it was mentioned that this test is useful only for compounds having less than six carbon atoms. Why is this so?
organic-chemistry alcohols
edited Aug 13 at 20:12
William R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
asked Aug 13 at 15:10
StackUpPhysicsStackUpPhysics
1899 bronze badges
$endgroup$
add a comment |
$begingroup$
I read about the Lucas test for alcohols in which a cloudy precipitate is produced with a tertiary or secondary alcohol. However, on a side note it was mentioned that this test is useful only for compounds having less than six carbon atoms. Why is this so?
organic-chemistry alcohols
edited Aug 13 at 20:12
William R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
asked Aug 13 at 15:10
StackUpPhysicsStackUpPhysics
1899 bronze badges
$endgroup$
$begingroup$
This "degre" nomenclature for alcohols is terribly outdated. Profs teaching that today are really old and have learned it from teachers which were already oldfashioned then.
$endgroup$
– Karl
Aug 14 at 5:51
add a comment |
$begingroup$
I read about the Lucas test for alcohols in which a cloudy precipitate is produced with a tertiary or secondary alcohol. However, on a side note it was mentioned that this test is useful only for compounds having less than six carbon atoms. Why is this so?
organic-chemistry alcohols
edited Aug 13 at 20:12
William R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
asked Aug 13 at 15:10
StackUpPhysicsStackUpPhysics
1899 bronze badges
$endgroup$
I read about the Lucas test for alcohols in which a cloudy precipitate is produced with a tertiary or secondary alcohol. However, on a side note it was mentioned that this test is useful only for compounds having less than six carbon atoms. Why is this so?
organic-chemistry alcohols
organic-chemistry alcohols
edited Aug 13 at 20:12
William R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
asked Aug 13 at 15:10
StackUpPhysicsStackUpPhysics
1899 bronze badges
edited Aug 13 at 20:12
William R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
asked Aug 13 at 15:10
StackUpPhysicsStackUpPhysics
1899 bronze badges
edited Aug 13 at 20:12
William R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
edited Aug 13 at 20:12
William R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
edited Aug 13 at 20:12
William R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
1,7601 gold badge5 silver badges23 bronze badges
asked Aug 13 at 15:10
StackUpPhysicsStackUpPhysics
1899 bronze badges
asked Aug 13 at 15:10
StackUpPhysicsStackUpPhysics
1899 bronze badges
asked Aug 13 at 15:10
StackUpPhysicsStackUpPhysics
1899 bronze badges
1899 bronze badges
$begingroup$
This "degre" nomenclature for alcohols is terribly outdated. Profs teaching that today are really old and have learned it from teachers which were already oldfashioned then.
$endgroup$
– Karl
Aug 14 at 5:51
add a comment |
$begingroup$
This "degre" nomenclature for alcohols is terribly outdated. Profs teaching that today are really old and have learned it from teachers which were already oldfashioned then.
$endgroup$
– Karl
Aug 14 at 5:51
$begingroup$
This "degre" nomenclature for alcohols is terribly outdated. Profs teaching that today are really old and have learned it from teachers which were already oldfashioned then.
$endgroup$
– Karl
Aug 14 at 5:51
$begingroup$
This "degre" nomenclature for alcohols is terribly outdated. Profs teaching that today are really old and have learned it from teachers which were already oldfashioned then.
$endgroup$
– Karl
Aug 14 at 5:51
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
The problem is that the alcohols themselves might be insoluble. Ethanol is soluble, yes, but as the alkyl chain length increases, the hydrophobic nature due to the chain starts dominating over whatever hydrophilicity the $ce-OH$ group had been providing for lower homologues.
From source [1]:
.. any alcohol that is insoluble in the reagent might appear to be giving a positive 3° test.
The paper goes on to properly quantify several things:
Based on the results of this study, using 1 drop of alcohol added to 10 drops of reagent, it can be said that, at the very least, all saturated acyclic monofunctional alcohols having six or fewer carbons are soluble in the Lucas reagent.
It is clear that the relative amounts of the sample and the reagent become important in such borderline cases (~6 carbon long chains). If too much alcohol is added, it may cause an illusion of positive lucas test.
From source [1]: (emphasis mine)
That statement may not be true when 3 or 4 drops are used
per 10 drops of reagent. In fact, sometimes when 10 drops of
reagent are added to 3 or 4 drops of some of the alcohols, an
interesting event occurs after a delay of a couple of minutes
or so. Apparently, some undissolved alcohol that has been
clinging to the bottom of the test tube suddenly breaks loose
and, by streaming to the surface of the very dense Lucas
reagent, gives a momentary illusion of a positive test. The
real cloudiness, alkyl chloride formation, appears later—all
the more reason to use a high reagent/alcohol ratio.
References:
[1] "A study of the Lucas test"
R. A. Kjonaas and B. A. Riedford
J. Chem. Ed. 1991 68 (8), 704
DOI: 10.1021/ed068p704
answered Aug 13 at 16:51
William R. EbenezerWilliam R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
$endgroup$
add a comment |
$begingroup$
To get a cloudy "precipitate", you need to dissolve the alcohol in the acid solution. Alcohols get less soluble in water as their chain length increases. By the time you pass 6 carbons, the alcohol itself is more or less insoluble. If it reacts along the interface, the chloride product would just mix into the alcohol layer, with no visible change.
answered Aug 13 at 16:30
jeffBjeffB
1,2213 silver badges10 bronze badges
$endgroup$
1
$begingroup$
Please share the reference you've used
$endgroup$
– StackUpPhysics
Aug 13 at 16:33
$begingroup$
I had no specific reference in mind, just general knowledge. The other answer is more complete than anything I had in mind.
$endgroup$
– jeffB
Aug 13 at 19:34
1
$begingroup$
no problem still I appreciate your efforts
$endgroup$
– StackUpPhysics
Aug 14 at 1:14
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
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votes
active
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votes
$begingroup$
The problem is that the alcohols themselves might be insoluble. Ethanol is soluble, yes, but as the alkyl chain length increases, the hydrophobic nature due to the chain starts dominating over whatever hydrophilicity the $ce-OH$ group had been providing for lower homologues.
From source [1]:
.. any alcohol that is insoluble in the reagent might appear to be giving a positive 3° test.
The paper goes on to properly quantify several things:
Based on the results of this study, using 1 drop of alcohol added to 10 drops of reagent, it can be said that, at the very least, all saturated acyclic monofunctional alcohols having six or fewer carbons are soluble in the Lucas reagent.
It is clear that the relative amounts of the sample and the reagent become important in such borderline cases (~6 carbon long chains). If too much alcohol is added, it may cause an illusion of positive lucas test.
From source [1]: (emphasis mine)
That statement may not be true when 3 or 4 drops are used
per 10 drops of reagent. In fact, sometimes when 10 drops of
reagent are added to 3 or 4 drops of some of the alcohols, an
interesting event occurs after a delay of a couple of minutes
or so. Apparently, some undissolved alcohol that has been
clinging to the bottom of the test tube suddenly breaks loose
and, by streaming to the surface of the very dense Lucas
reagent, gives a momentary illusion of a positive test. The
real cloudiness, alkyl chloride formation, appears later—all
the more reason to use a high reagent/alcohol ratio.
References:
[1] "A study of the Lucas test"
R. A. Kjonaas and B. A. Riedford
J. Chem. Ed. 1991 68 (8), 704
DOI: 10.1021/ed068p704
answered Aug 13 at 16:51
William R. EbenezerWilliam R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
$endgroup$
add a comment |
$begingroup$
The problem is that the alcohols themselves might be insoluble. Ethanol is soluble, yes, but as the alkyl chain length increases, the hydrophobic nature due to the chain starts dominating over whatever hydrophilicity the $ce-OH$ group had been providing for lower homologues.
From source [1]:
.. any alcohol that is insoluble in the reagent might appear to be giving a positive 3° test.
The paper goes on to properly quantify several things:
Based on the results of this study, using 1 drop of alcohol added to 10 drops of reagent, it can be said that, at the very least, all saturated acyclic monofunctional alcohols having six or fewer carbons are soluble in the Lucas reagent.
It is clear that the relative amounts of the sample and the reagent become important in such borderline cases (~6 carbon long chains). If too much alcohol is added, it may cause an illusion of positive lucas test.
From source [1]: (emphasis mine)
That statement may not be true when 3 or 4 drops are used
per 10 drops of reagent. In fact, sometimes when 10 drops of
reagent are added to 3 or 4 drops of some of the alcohols, an
interesting event occurs after a delay of a couple of minutes
or so. Apparently, some undissolved alcohol that has been
clinging to the bottom of the test tube suddenly breaks loose
and, by streaming to the surface of the very dense Lucas
reagent, gives a momentary illusion of a positive test. The
real cloudiness, alkyl chloride formation, appears later—all
the more reason to use a high reagent/alcohol ratio.
References:
[1] "A study of the Lucas test"
R. A. Kjonaas and B. A. Riedford
J. Chem. Ed. 1991 68 (8), 704
DOI: 10.1021/ed068p704
answered Aug 13 at 16:51
William R. EbenezerWilliam R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
$endgroup$
add a comment |
$begingroup$
The problem is that the alcohols themselves might be insoluble. Ethanol is soluble, yes, but as the alkyl chain length increases, the hydrophobic nature due to the chain starts dominating over whatever hydrophilicity the $ce-OH$ group had been providing for lower homologues.
From source [1]:
.. any alcohol that is insoluble in the reagent might appear to be giving a positive 3° test.
The paper goes on to properly quantify several things:
Based on the results of this study, using 1 drop of alcohol added to 10 drops of reagent, it can be said that, at the very least, all saturated acyclic monofunctional alcohols having six or fewer carbons are soluble in the Lucas reagent.
It is clear that the relative amounts of the sample and the reagent become important in such borderline cases (~6 carbon long chains). If too much alcohol is added, it may cause an illusion of positive lucas test.
From source [1]: (emphasis mine)
That statement may not be true when 3 or 4 drops are used
per 10 drops of reagent. In fact, sometimes when 10 drops of
reagent are added to 3 or 4 drops of some of the alcohols, an
interesting event occurs after a delay of a couple of minutes
or so. Apparently, some undissolved alcohol that has been
clinging to the bottom of the test tube suddenly breaks loose
and, by streaming to the surface of the very dense Lucas
reagent, gives a momentary illusion of a positive test. The
real cloudiness, alkyl chloride formation, appears later—all
the more reason to use a high reagent/alcohol ratio.
References:
[1] "A study of the Lucas test"
R. A. Kjonaas and B. A. Riedford
J. Chem. Ed. 1991 68 (8), 704
DOI: 10.1021/ed068p704
answered Aug 13 at 16:51
William R. EbenezerWilliam R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
$endgroup$
The problem is that the alcohols themselves might be insoluble. Ethanol is soluble, yes, but as the alkyl chain length increases, the hydrophobic nature due to the chain starts dominating over whatever hydrophilicity the $ce-OH$ group had been providing for lower homologues.
From source [1]:
.. any alcohol that is insoluble in the reagent might appear to be giving a positive 3° test.
The paper goes on to properly quantify several things:
Based on the results of this study, using 1 drop of alcohol added to 10 drops of reagent, it can be said that, at the very least, all saturated acyclic monofunctional alcohols having six or fewer carbons are soluble in the Lucas reagent.
It is clear that the relative amounts of the sample and the reagent become important in such borderline cases (~6 carbon long chains). If too much alcohol is added, it may cause an illusion of positive lucas test.
From source [1]: (emphasis mine)
That statement may not be true when 3 or 4 drops are used
per 10 drops of reagent. In fact, sometimes when 10 drops of
reagent are added to 3 or 4 drops of some of the alcohols, an
interesting event occurs after a delay of a couple of minutes
or so. Apparently, some undissolved alcohol that has been
clinging to the bottom of the test tube suddenly breaks loose
and, by streaming to the surface of the very dense Lucas
reagent, gives a momentary illusion of a positive test. The
real cloudiness, alkyl chloride formation, appears later—all
the more reason to use a high reagent/alcohol ratio.
References:
[1] "A study of the Lucas test"
R. A. Kjonaas and B. A. Riedford
J. Chem. Ed. 1991 68 (8), 704
DOI: 10.1021/ed068p704
answered Aug 13 at 16:51
William R. EbenezerWilliam R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
answered Aug 13 at 16:51
William R. EbenezerWilliam R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
answered Aug 13 at 16:51
William R. EbenezerWilliam R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
answered Aug 13 at 16:51
William R. EbenezerWilliam R. Ebenezer
1,7601 gold badge5 silver badges23 bronze badges
1,7601 gold badge5 silver badges23 bronze badges
add a comment |
add a comment |
$begingroup$
To get a cloudy "precipitate", you need to dissolve the alcohol in the acid solution. Alcohols get less soluble in water as their chain length increases. By the time you pass 6 carbons, the alcohol itself is more or less insoluble. If it reacts along the interface, the chloride product would just mix into the alcohol layer, with no visible change.
answered Aug 13 at 16:30
jeffBjeffB
1,2213 silver badges10 bronze badges
$endgroup$
1
$begingroup$
Please share the reference you've used
$endgroup$
– StackUpPhysics
Aug 13 at 16:33
$begingroup$
I had no specific reference in mind, just general knowledge. The other answer is more complete than anything I had in mind.
$endgroup$
– jeffB
Aug 13 at 19:34
1
$begingroup$
no problem still I appreciate your efforts
$endgroup$
– StackUpPhysics
Aug 14 at 1:14
add a comment |
$begingroup$
To get a cloudy "precipitate", you need to dissolve the alcohol in the acid solution. Alcohols get less soluble in water as their chain length increases. By the time you pass 6 carbons, the alcohol itself is more or less insoluble. If it reacts along the interface, the chloride product would just mix into the alcohol layer, with no visible change.
answered Aug 13 at 16:30
jeffBjeffB
1,2213 silver badges10 bronze badges
$endgroup$
1
$begingroup$
Please share the reference you've used
$endgroup$
– StackUpPhysics
Aug 13 at 16:33
$begingroup$
I had no specific reference in mind, just general knowledge. The other answer is more complete than anything I had in mind.
$endgroup$
– jeffB
Aug 13 at 19:34
1
$begingroup$
no problem still I appreciate your efforts
$endgroup$
– StackUpPhysics
Aug 14 at 1:14
add a comment |
$begingroup$
To get a cloudy "precipitate", you need to dissolve the alcohol in the acid solution. Alcohols get less soluble in water as their chain length increases. By the time you pass 6 carbons, the alcohol itself is more or less insoluble. If it reacts along the interface, the chloride product would just mix into the alcohol layer, with no visible change.
answered Aug 13 at 16:30
jeffBjeffB
1,2213 silver badges10 bronze badges
$endgroup$
To get a cloudy "precipitate", you need to dissolve the alcohol in the acid solution. Alcohols get less soluble in water as their chain length increases. By the time you pass 6 carbons, the alcohol itself is more or less insoluble. If it reacts along the interface, the chloride product would just mix into the alcohol layer, with no visible change.
answered Aug 13 at 16:30
jeffBjeffB
1,2213 silver badges10 bronze badges
answered Aug 13 at 16:30
jeffBjeffB
1,2213 silver badges10 bronze badges
answered Aug 13 at 16:30
jeffBjeffB
1,2213 silver badges10 bronze badges
answered Aug 13 at 16:30
jeffBjeffB
1,2213 silver badges10 bronze badges
1,2213 silver badges10 bronze badges
1
$begingroup$
Please share the reference you've used
$endgroup$
– StackUpPhysics
Aug 13 at 16:33
$begingroup$
I had no specific reference in mind, just general knowledge. The other answer is more complete than anything I had in mind.
$endgroup$
– jeffB
Aug 13 at 19:34
1
$begingroup$
no problem still I appreciate your efforts
$endgroup$
– StackUpPhysics
Aug 14 at 1:14
add a comment |
1
$begingroup$
Please share the reference you've used
$endgroup$
– StackUpPhysics
Aug 13 at 16:33
$begingroup$
I had no specific reference in mind, just general knowledge. The other answer is more complete than anything I had in mind.
$endgroup$
– jeffB
Aug 13 at 19:34
1
$begingroup$
no problem still I appreciate your efforts
$endgroup$
– StackUpPhysics
Aug 14 at 1:14
1
1
$begingroup$
Please share the reference you've used
$endgroup$
– StackUpPhysics
Aug 13 at 16:33
$begingroup$
Please share the reference you've used
$endgroup$
– StackUpPhysics
Aug 13 at 16:33
$begingroup$
I had no specific reference in mind, just general knowledge. The other answer is more complete than anything I had in mind.
$endgroup$
– jeffB
Aug 13 at 19:34
$begingroup$
I had no specific reference in mind, just general knowledge. The other answer is more complete than anything I had in mind.
$endgroup$
– jeffB
Aug 13 at 19:34
1
1
$begingroup$
no problem still I appreciate your efforts
$endgroup$
– StackUpPhysics
Aug 14 at 1:14
$begingroup$
no problem still I appreciate your efforts
$endgroup$
– StackUpPhysics
Aug 14 at 1:14
add a comment |
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$begingroup$
This "degre" nomenclature for alcohols is terribly outdated. Profs teaching that today are really old and have learned it from teachers which were already oldfashioned then.
$endgroup$
– Karl
Aug 14 at 5:51